Multiple-grid thermionic tube



Oct. 28, 1930.

s. LOEWE MULTI PLE GRID THE-RMIONIC TUBE Filed July 1926 v 1 practice the Patented a. 28, 1930 UNITED STATES PATENT o FrcE SIEGMUND :LOEWE, OF GERMANY, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE MULTIPLE-GRID THERMIONIO TUBE Application filed July 27, 1926, Serial No.

This invention relates to a thermionic tube havin a plurality of grids, which may especially e used for so-called compensatin connections, whereby sums or differences 0 elec- 6 trical currents have to be formed.

Especially for connections serving for the suppression of disturbances it is necessary to form the electrical difference of two simultaneously occurring receiving actions, of which 1 for instance the one receiving action consists of the disturbances alone, and the other re ceiving action consists of the sum of the reception proper and the disturbances. A rece tion of this kind may, for instance, be 0 tained by two similar receiving sets, of which one set is sharply tuned to the wave to be received, while the other set is adjusted for a wave which is slightly difierent from the former wave. In order to suppress the disturbances, it will only be necessary to form the electrical diiference between the two receiving actions.

The accompanying drawing shows diagrammatic representations of two forms of multiple grid tubes according to this invention, one form being shown in Fig. 1 and the other form in Fig. 2 in a view taken perpendicularly to the anode, grid and filament system. Fig. 3 is a section through the anode, grid and filament system of Fig. 2.

In Fig. 1 the incandescent filament or cathode is designated by the numeral 1, while the numerals 2 and 3 refer to parallelly wound grids, which are insulated from each other. The anode is designated by the numeral 4.

The entire system is mounted within a lassbulb 5 and comprises two leads 6 and for the heating filament, two leads 8 and 9 for the grids and a lead 10 for the anode. In heating filament is preferably stretched out in a straight line between the two grids, and positioned as symmetrically as possible with regard to the latter, while the anode surrounds the entire system symmetrically. For practical connections the tube is used in such a way, that the one receiving action is caused to play between the cathode and the one grid 2, and the other receiving action between the same cathode and the second grid 3. In this manner the sum 125,312, and in Germany August 1, 1925.

of the receiving actions will be obtained. In i order to form the difference between the two rece ving actions the phase of the one receiving action is displaced by 180, or a tube is interposed with reversed connections.

The tube as above described, may be improved in such a way, thatthe advantages of the double-gird tube may be utilized simultaneously. In Fig. 2 a tube of this kind is represented, having a space charging grid. Fig. 2 also shows another construction of the compensating grid. The leads for the oathode are again designated by the numerals 6 and 7, while the leads for the two compensating grlds are designated by the numerals 8 and 9. The space charging grid is represented at 11. The compensating grid consists of two grid systems, of which one is placed within the other. 'The one system is fastened to a ring 12 and the other system to a like ring 13, The bars of the combined grid system are distributed over a cylinder surface in such a manner that alternately a bar of one grid system is connected to the ring 12, and a liar of the other system to the ring 13. Within the space, which is surrounded by the combined system of the grid bars, there is placed the straight incandescent cathode 1, the space charging grid 11, and in addition thereto the concentrically arranged anode 4. In Fig. 3, which is a cross-section through Fig. 2 the glass-bulb is represented at 14. The cylindrical anode is shown at 4 and the rings at 13. These rings carry alternately the grid bars, which are connected to the same. 11 is the space charging grid, which is formed, for instance, by a spiral, said spiral appearing in its projection as a circle, the point 1 in the centre representing the straight cathode as seen in its projection. In a compensating grid tube of this kind having a protective screen, the interior grid 11 would have to be omitted and substituted by a screen placed between the rings '12 and 13 and the anode 4.

In many cases of connections, the special space charging grid or anode protecting screen grid may be dispensed with, and one or both compensating grids may be used simultaneously for this purpose.

I claim:

1. A multiple grid thermionic tube, comprising a plurality of ids adapted to exert the same tube control ing action, an anode positioned concentricall with respect to said grids, and an additiona grid adapted to act as a space charging grid or protective screen for said anode.

' 2. A multiple grid thermionic tube, comprising two grids which are insulated from each other and adapted to exert the same tube controlling action, each of said rids consisting'of a ring with grid bars astened perendicularly thereon, said rings and grid bars of each grid being positioned relatively to each other to form a combined cylindrical rid system having grid bars which alternatefi belong to the one and the other grid, a filament placed essentially in the direction of the axis of said combined cylindrical grid systems, an anode concentrically mounted with respect to the combined grid system, and a third grid adapted to act as a space chagging grid or protecting screen for said ano e.

In testimony whereof I have afiixed my signature.

SIEG LOEWE. 

